The present invention is directed to a grinding head used in a machine for grinding helically grooved cutting tools. The grinding head includes a rotatable spindle with carriages supporting the spindle so that it can be displaced about a pair of perpendicular axes. The grinding head can be reciprocated along one axis and it can be pivoted about another axis.
In a known universal tool grinding machine in addition to the vertically arranged grinding head carrier, a grinding table is used for supporting the tool carrier and the grinding table is supported so that it can be pivoted about a vertical axis while the table moves reciprocally or back and forth in the horizontal direction. The grinding table supports the grinding head carrier. The workpiece to be ground is adjusted by the tool carrier with reference to a grinding disc so that the surface to be ground coincides with a horizontal pivot axis of a surface plate defined by a stop projection. The grinding disc is adjusted by carriages or slides so that it contacts the surface of the workpiece to be ground before the grinding process can be carried out. If the grinding disc in such a grinding head is adjusted to the helix angle of the cutting tool, the working point of the grinding disc moves out of the axial center and intersects the cutting tool perpendicularly relative to the rotational axis during subsequent grinding, since the grinding disc can be moved along the vertical Z-axis of the grinding head during the grinding operation. Accordingly, a desired rake angle can be achieved only by approximation of simultaneous adjustment in the direction of the Z and Y axes. Previously, the extent of the adjusting motions were determined only by sample grinding of a cutting tool and taking subsequent measurements and making repeated corrections in the adjusting values. In other words, if the forward feed movement of the carriages must be adjusted to the diameter of the tool to be ground, but are referred to the axial center of the tool in the previously known arrangement, the rake angle of helically grooved cutting tools can be ground only in an approximate manner in such a tool grinding machine. Further, varying rake angles are produced in the cutting tool in numerically controlled grinding operations.